The formation and evolution of planetary systems

especially on the various processes which create surprisingly complex chemistry there. Next ANDERSconsiders primitive meteorites. which include both “presolar” material (which retains its original isotopic composition) and processed matter, in which isotopic anomalies were lost in the early solar system. Comet nuclei, presumably subjected to very limited processing, should be intermediate between the “raw material” of the interstellar medium and primitive meteorites. Brownlee particles (microscopic bits of dust collected in the stratosphere by U2 aircraft) and larger fragments from deep-sea sediments provide the most direct sampling of inte~laneta~ dust. BROWNLEE'S paper compares these particles with meteorites and models of cometary dust: the hydrated particles arc similar to types of the unusual carbonaceous chondrites, with the anhydrated dust probably of cometary origin. The analysis is continued by PILLINGER,who presents laboratory studies of stable isotopes in both meteorites and dust grains. Comparing observational and theoretical results with these direct experiments promises much for the future. The recent past has finally produced a satisl‘actory mechanism to explain the prominent Kirkwood gap in asteroid orbits at the 3:l resonance with Jupiter’s period. WETHERILL’S ~ont~bution describes how fragments of asteroids produced at this resonance may collide with the Earth within a few million years, plausibly the source of the great majority of the ordinary chondritic meteorites. The chapters on comets include an overview by WHIPPLEwhich considers their gaseous composition and the likelihood that some short-period comets eventually become inactive, thereby being labeled asteroids. HUGHESreviews the history of Comet Halley on time scales of billions of years to the last few centuries, followed by three papers (by MEADOWS,MCDONNELLet al., and ENCRENAZ)on preliminary results from Halley’s recent perihelion passage from both ground-

based and spacecrah observations. W’IiIPPLE’sdirt! 1tehei-gme&i I; comet nuclei is confirmed as expected, with watc’r ice dominatin&. the volatiles, although of course details (sporadic activity, variety (I!’ dust composition) provide complications. The rnic oi‘ carbon in ftu outer solar system needs more uIldL,rstanding. with tht‘ Vega f spacecraft indicating carbon in Halley*c volatiles is primarily c‘(+ ,anti more recently Voyager 2 implying (‘l-i, captured the carbon at f ntun. leaving CO less abundant than might be expectcc!. RIWLEY’Sinterpretation of the solar wmd-comet imeraction from the ICE encounter with Comet ~iacobini-Z~n~~er was the high point of the book for me; injecting cold neutral gas into a supersonic magnetized plasma with ionizing photons is a fascinatmg physics cxpcr iment. CLUBE offers a more speculative paper. proposing that th<, present Zodiacal Light is mainly debris from a singlo comet, anri finally BRAN~T provides a summary of the currem unders~ndil~~ of comets. Most of the misprints in the book should cauw no confuston, hut “c - 0.6” on page 76 should be e (for eccentricit! I -0.h. and tht rate long-period comets become short-period comets. listed as one per thou~ndth of a year on p. 175. apparently should be once per thousand years. The volume was informative and I enjoyed readmg it. But its price makes it unlikely to be purchased hy many individuals, libraries are likely to have the original journal with the same articles. and its lark of an index severely diminishes its value for reference.

The Form&on and Evolution ofPlaneturf Systems edited by H. A. Weaver and L. Danly. Cambridge Universtty Press, 1989. xi f 344p.. US $50.00 (ISBN O-521-36633-X).

troductory remarks by C. A. Norman, are: “Making the Solar Systern”--A. G. W. Cameron; “Formation of the Proto-Sun and the Evolution of the Solar Nebula Mechanism of Angular Momentum Transfer”-& M. Miyama; “The Chemical Record“--Cl. J. Wasserhurg: “Summarizing Remarks on the Astronomical Evidence for Circumstellar Disks”-G. H. Herbig; “Which Stars Have Planets?“J. J. Lissauer: “Cosmochemistry”-J. S. Lewis: “Dynamical Properties of Protoplane~~ Disks”-D. N. C. Lin. Finally, Chapter 13, entitled “instrumentation for the Study of Planetary Systems,” consists of a seriatim description of 13 instruments and/or planetary spacecraft missions, each described by l-h authors involved with the instrument ormission. Except for Chapter 8 by Norman and Paresce, each of Chapters I- I 1 and each section of Chapter 12 is followed by a short question/answer type discussion recorded at the meeting. Most of these discussions do not generally add much to the review or section, hut they sometimes underline the existence of dissenting views. The meat of this book is in the t i review chapters, with the most informative to me being those by Norman and Paresce and by Bodenheimer. The chapters are uniformly thorough and up-to-date. with the overwhelming majority of references in each being to publications in the 1980s. Chapter I2 might have been even more useful to the readers. if the author of each section had had lime to compose it at leisure, rather than in “real time”. From a technical standpoint, the hook is well prepared, with very few typographical errors (and nearly all of these are of the data is/are variety). In fact. I found only one other, on p. 294. I would characterize the book as being a very useful summa~ for those interested in planetary (solar) system formation. Certainly, I gained more knowledge and appreciation of the topic and 1recommend the book to those interested in the question of whether other planetary systems exist and whether it is thought that they formed as our Solar System did. My reading of the arguments is that the answers to both questions is “probably yes”. However, the observational base is likely to change in the near future so that a new workshop early in the 2 1st century might reach other conclusions. I can hardly wait.

SCIENTISTS ARE HUMAN.We want our reach to exceed OUF grasp. So. well before we establish how our Solar System formed. we wish to understand whether there are other systems and to what extent our own System and its fo~ation mechanisms are prototypical of these other ones (if they exist). The situation is examined in this volume, number 3 in the Space Telescope= Science Institute Symposium Series, which is the proceedings of a 3-day meeting of the same title held at Baltimore on 9-I I May 1988. As the editors state in a ‘-page intr~uction, “The goal of the workshop was to bring together stellar and planetary scientists to review our present understanding of planetary system development in the context of star formation, to identify and address the outstanding problems in the field, and to provide a focus for future observational and theoretical work.” The book consists of 13 chapters, the first 11 of which each reviews. in an excellent and up-to-date fashion the current status of a topic relevant to planetary system formation. The titles and authors of the HurstI I chapters are: “The Formation of the Solar System: Consensus, Ahematives, and Missing Factors”---G. W. Wethetill; “The Evolution of Protostellar Disks”--R. B. Larson; “On the Relationship Between Earlv Solar Activitv and the Evolution of Terrestrial Planet Atmospheres”-% 0. Pkpin; “Implications of the Giant Planets for the Formation and Evolution of Planetary Systems”-D. J. Stevenson: “Constraints on the Properties and Environment of Primitive Stellar Nebulae from the Astrophysical Record Provided by Young Stellar Objects”-& E. Strom, S. Edwards, and K. M. Strom; “Molecular Disks and Their Link to Planetary Systems”-A. 1. Sargent; “The Physics of Planetesimal Formation”-S. J. Weidenschilhng, B. Dorm, and P. Meakin; “Circumstellar Material Around Nearby Stars: Clues to the Formation of Planetary Systems”-C. A. Norman and I. Paresee: “Solar Nebula Chemist@ Impli~tions for Volatiles in the Solar System”-B. Fegley Jr. and R. G. Prinn; “Primitive Bodies: Molecular Abundances in Comet Halley as Probes of Cometary Formation Environments”-J. I. Lunine;.and “The Impact of Stellar Evolution in Planetarv System Develoument”-F. Bodenheimer. Chapter 12, entitI~~‘~ajor Issues in Planetary System Formation.” consists of 7 sections written by session chairmen, outlining their thoughts on the session topics. The sections, which follow brief in-

Michael E. Lipschutz M/ LJafhyette. IN 47907, USA